1. Field of the Invention
The present invention relates to single ended oscillators, and more specifically to generating a 50% duty cycle output signal using a single ended crystal oscillator.
2. Background Art
A crystal oscillator is a popularly used circuit block in an integrated circuit (IC), when a highly accurate clock is required. Often, a 50% duty cycle clock is preferred. The conventional configuration to generate a 50% duty cycle uses a differential crystal oscillator design. However, differential designs are difficult to design and generally more complicated. Another conventional technique is to use a single-ended design having a replica circuit to set the DC point which is used to compare with the oscillation waveform. Both configurations require significant current, and the latter one also introduces an inaccuracy because the replica circuit cannot generate an accurate copy of the DC component of the oscillation signal.
It is highly desirable to reduce current consumption so as to reduce overall power requirements. Therefore, what is needed is a crystal oscillator design that can generate an accurate 50% duty cycle oscillator signal with reduced current compared to conventional designs.